Both of those statistics seem accurate, though I haven't looked up the exact numbers. Making food safe cultures and enzymes is a complicated process, so most cheesemakers buy them from specialty companies with reputations for quality. Even if they're made by the same company, there are many different cultures to choose from, and they'll act differently depending on the milk and other factors during the make.

Most of the milk that we drink in the U.S. comes from Holstein cows because they have the highest milk production of all cattle breeds. We have brown swiss cows because, while they do produce slightly less milk than holsteins, their milk has a lot of protein and butterfat for cheesemaking, and they're well suited for grazing on pastures.